Salmonella typhimurium and Salmonella enteritidis: changing epidemiology from 1973 until 1992.

A retrospective analysis, covering a period of 20 years, of 2049 primo-isolates of Salmonella typhimurium and 343 primo-isolates of Salmonella enteritidis was performed at our laboratory. In 1991, S. enteritidis (43.8%) outnumbered S. typhimurium (32.1%) as the most frequently isolated Salmonella. The age group distribution of S. enteritidis yielded peaks in the under-five and above-60 year age groups, whereas S. typhimurium only peaked in the under-five age group. S. enteritidis appeared to be twice as invasive as S. typhimurium. Both serotypes were more invasive in middle and older age groups than in under-fives.